A gas turbine is composed of a compressor, a combustor, and a turbine. In the compressor, air taken in through an air intake opening is compressed into high-temperature, high-pressure compressed air, and in the combustor, fuel is supplied to this compressed air and the mixture is combusted to produce high-temperature, high-pressure combustion gas (working fluid). The turbine is driven by this combustion gas, and thereby a generator coupled to the turbine is driven. The combustion gas having driven the turbine is discharged as exhaust gas from the exhaust side of the turbine. The gas turbine further has a cooling air supply line through which cooling air is supplied to the turbine.
A control system that controls such a gas turbine executes temperature adjustment control that involves adjusting the amount of air taken into the compressor, the supply amount of fuel, the supply amount of cooling air, etc., and thereby controlling the operation of the gas turbine so that the turbine inlet temperature of the turbine into which the combustion gas flows does not exceed a preset upper limit temperature. For example, Patent Literature 1 describes a gas turbine control system that performs such temperature adjustment control. The operation control system for a gas turbine described in Patent Literature 1 adjusts the opening degree of an air intake valve (inlet guide vane), provided on the intake side of the compressor, to a larger opening degree as the gas turbine output increases.